Lipid Peroxidation and Antioxidant Status in Stomach Cancer

Membrane Lipid Replacement for reconstituting mitochondrial function and moderating cancer-related fatigue, pain and other symptoms while counteracting the adverse effects of cancer cytotoxic therapy

Cancer-related fatigue, pain, gastrointestinal and other symptoms are among the most familiar complaints in practically every type and stage of cancer, especially metastatic cancers. Such symptoms are also related to cancer oxidative stress and the damage instigated by cancer cytotoxic therapies to cellular membranes, especially mitochondrial membranes. Cancer cytotoxic therapies (chemotherapy and radiotherapy) often cause adverse symptoms and induce patients to terminate their anti-neoplastic regimens. Cancer-related fatigue, pain and other symptoms and the adverse effects of cancer cytotoxic therapies can be safely moderated with oral Membrane Lipid Replacement (MLR) glycerolphospholipids and mitochondrial cofactors, such as coenzyme Q10. MLR provides essential membrane lipids and precursors to maintain mitochondrial and other cellular membrane functions and reduces fatigue, pain, gastrointestinal, inflammation and other symptoms. In addition, patients with a variety of chronic symptoms benefit from MLR supplements, and MLR also has the ability to enhance the bioavailability of nutrients and slowly remove toxic, hydrophobic molecules from cells and tissues.

Development of a prognostic metabolic signature in stomach adenocarcinoma

PURPOSE

The growth and aggressiveness of Stomach adenocarcinoma (STAD) is significantly affected by basic metabolic changes. This study aimed to identify metabolic gene prognostic signatures in STAD.

METHODS

An integrative analysis of datasets from the Cancer Genome Atlas and Gene Expression Omnibus was performed. A metabolic gene prognostic signature was developed using univariable Cox regression and Kaplan-Meier survival analysis. A nomogram model was developed to predict the prognosis of STAD patients. Finally, Gene Set Enrichment Analysis (GESA) was used to explore the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways significantly associated with the risk grouping.

RESULTS

A total of 327 metabolism-related differentially expressed genes were identified. Three subtypes of STAD were identified and nine immune cell types, including memory B cell, resting and activated CD4+ memory T cells, were significantly different among the three subgroups. A risk score model including nine survival-related genes which could separate high-risk patients from low-risk patients was developed. The prognosis of STAD patients likely benefited from lower expression levels of genes, including ABCG4, ABCA6, GPX8, KYNU, ST8SIA5, and CYP19A1. Age, radiation therapy, tumor recurrence, and risk score model status were found to be independent risk factors for STAD and were used for developing a nomogram. Nine KEGG pathways, including spliceosome, pentose phosphate pathway, and citrate TCA cycle were significantly enriched in GESA.

CONCLUSION

We propose a metabolic gene signature and a nomogram for STAD which might be used for predicting the survival of STAD patients and exploring prognostic markers.

Increased Oxidative Stress in Gastric Cancer Patients and Their First-Degree Relatives: A Prospective Study from Northeastern Brazil

Background and Aims

First-degree relatives of gastric cancer patients are at increased risk of developing gastric cancer. Increased oxidative stress, including lipid peroxidation, has been associated with gastric carcinogenesis. Whether first-degree relatives of gastric cancer patients have increased oxidative stress remains unknown. We aimed to compare oxidative stress in patients with gastric cancer, their first-degree relatives, and dyspeptic controls.

Methods

A total of 155 patients undergoing upper endoscopy were prospectively enrolled, including 50 with gastric cancer, 49 first-degree relatives of gastric cancer patients, and 56 controls. Serum concentrations of malondialdehyde (MDA) and glutathione) and activities of superoxide dismutase (SOD) and catalase were measured. Multivariate analysis adjusting for sex, age, smoking status, and alcohol consumption was performed.

Results

Lipid peroxidation, as measured by concentration of MDA (nmol/mL), was higher (p = 0.04), and glutathione levels were lower (p < 0.001) in the gastric cancer group compared to controls. There was no difference in the catalase activity among the groups. There was no difference in glutathione and MDA concentration or catalase activity between the different stages of gastric cancer based on the TNM classification. Relatives of gastric cancer patients had higher glutathione concentration (μmol/mL) compared to gastric cancer patients (262.5 vs. 144.6; p = 0.018), while there was no difference in MDA concentration. Catalase and superoxide dismutase activity were lower in the gastric cancer group (3.82 vs. 0.91; p < 0.001 and 1.04 vs. 0.6; p < 0.001) compared to their first-degree relatives. Interestingly, MDA concentration in the first-degree relative group was higher than in the control group (7.9 vs. 5.1; p = 0.03).

Conclusions

In this study, similarly to gastric cancer patients, their first-degree relatives were found to have increased oxidative stress compared to controls. Further studies are warranted to validate this observation and to better understand the role of oxidative stress as a possible biomarker in this population.

Therapeutic Influence on Important Targets Associated with Chronic Inflammation and Oxidative Stress in Cancer Treatment

Simple Summary

There is no doubt that the need for new effective methods of cancer treatment remains challenging, as cancer is the second cause of death based on the number of cases in the world. In this review, we investigated the role of one of the leading determinants in the development and progression of various types of cancer—oxidative stress and inflammation, as well as clinical and experimental data from the studies of promising drugs of natural origin, such as flavonoids, that target these stages of oncogenesis. This can all help in the expansion and systematization of the existing knowledge regarding the fight against cancer, the facilitation of the development of effective anti-cancer drugs, and the progression of research in this field, in order to improve the treatment of these disorders.

Abstract

Chronic inflammation and oxidative stress are the interconnected pathological processes, which lead to cancer initiation and progression. The growing level of oxidative and inflammatory damage was shown to increase cancer severity and contribute to tumor spread. The overproduction of reactive oxygen species (ROS), which is associated with the reduced capacity of the endogenous cell defense mechanisms and/or metabolic imbalance, is the main contributor to oxidative stress. An abnormal level of ROS was defined as a predisposing factor for the cell transformation that could trigger pro-oncogenic signaling pathways, induce changes in gene expression, and facilitate accumulation of mutations, DNA damage, and genomic instability. Additionally, the activation of transcription factors caused by a prolonged oxidative stress, including NF-κB, p53, HIF1α, etc., leads to the expression of several genes responsible for inflammation. The resulting hyperactivation of inflammatory mediators, including TNFα, TGF-β, interleukins, and prostaglandins can contribute to the development of neoplasia. Pro-inflammatory cytokines were shown to trigger adaptive reactions and the acquisition of resistance by tumor cells to apoptosis, while promoting proliferation, invasion, and angiogenesis. Moreover, the chronic inflammatory response leads to the excessive production of free radicals, which further aggravate the initiated reactions. This review summarizes the recent data and progress in the discovery of mechanisms that associate oxidative stress and chronic inflammation with cancer onset and metastasis. In addition, the review provides insights for the development of therapeutic approaches and the discovery of natural substances that will be able to simultaneously inhibit several key oncological and inflammation-related targets.

Evaluation and Monitoring of Superoxide Dismutase (SOD) Activity and its Clinical Significance in Gastric Cancer: A Systematic Review and Meta-Analysis

Background

This systematic review of the literature and meta-analysis aimed to review the evaluation and monitoring of superoxide dismutase (SOD) activity and its clinical significance in gastric cancer.

Material/Methods

Systematic review involved searching the PubMed, Embase, Ovid, and the China National Knowledge Infrastructure (CNKI) databases. Search terms included ‘superoxide dismutase,’ and ‘gastric cancer.’ Studies that included measurements of SOD activity in peripheral blood samples in patients with SOD activity compared with healthy controls. The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

Results

Ten controlled clinical studies were identified that included six studies that measured SOD in serum, three in erythrocytes, and one study that measured SOD on whole blood. Meta-analysis, using the standardized mean difference (SMD) and the 95% confidence interval (CI), showed that patients with gastric cancer had significantly decreased SOD activity when compared with the healthy controls (SMD, −0.840; 95% CI, −1.463 to −0.218; p=0.008). Subgroup analysis was conducted on SOD distribution in the blood (erythrocyte: SMD, −1.773; 95% CI, −2.504 to −1.042; p=0.000) (serum SMD, −0.322; 95% CI, −1.006−0.361; p=0.355) (whole blood: SMD, −1.251; 95% CI, −1.731 to −0.771; p=0.000) and for male subjects (SMD, −2.090; 95% CI, −2.725 to −1.456; p<0.001).

Conclusions

Meta-analysis showed that SOD measurements from blood samples, especially in erythrocytes, had potential as a diagnostic and monitoring parameter in patients with gastric cancer.

The Emerging Role of Estrogens in Thyroid Redox Homeostasis and Carcinogenesis

Reactive oxygen species (ROS) are the most critical class of free radicals or reactive metabolites produced by all living organisms. ROS regulate several cellular functions through redox-dependent mechanisms, including proliferation, differentiation, hormone synthesis, and stress defense response. However, ROS overproduction or lack of appropriate detoxification is harmful to cells and can be linked to the development of several diseases, such as cancer. Oxidative damage in cellular components, especially in DNA, can promote the malignant transformation that has already been described in thyroid tissue. In thyrocyte physiology, NADPH oxidase enzymes produce large amounts of ROS that are necessary for hormone biosynthesis and might contribute to the high spontaneous mutation rate found in this tissue. Thyroid cancer is the most common endocrine malignancy, and its incidence is significantly higher in women than in men. Several lines of evidence suggest the sex hormone estrogen as a risk factor for thyroid cancer development. Estrogen in turn, besides being a potent growth factor for both normal and tumor thyroid cells, regulates different mechanisms of ROS generation. Our group demonstrated that the thyroid gland of adult female rats exhibits higher hydrogen peroxide (H₂O₂) production and lower enzymatic antioxidant defense in comparison with male glands. In this review, we discuss the possible involvement of thyroid redox homeostasis and estrogen in the development of thyroid carcinogenesis.

Levels of malondialdehyde in the gastric juice: Its association with Helicobacter pylori infection and stomach diseases

BACKGROUND

Helicobacter pylori (H. pylori) infection causes elevation of lipid peroxidation product malondialdehyde (MDA) and this association may be due to the bacterium causing reactive oxygen species-mediated damage to DNA in the gastric epithelium. The aim of this study was to investigate the gastric juice MDA levels in relation to H. pylori infection and associated gastric diseases.

METHODS

Gastric juice samples were obtained from 117 patients undergoing endoscopy, and gastric juice MDA levels were determined by high-performance liquid chromatography (HPLC) system. We compared the MDA levels between patients with and without H. pylori infection and assessed the differences of MDA levels between chronic gastritis, gastric intestinal metaplasia, and gastric cancer postsurgical resection.

RESULTS

Malondialdehyde levels in gastric juice were significantly higher in chronic gastritis patients with H. pylori infection than in those without H. pylori infection (P < .0001). In patients without H. pylori infection, patients with gastric intestinal metaplasia and gastric cancer postsurgical resection had significantly higher gastric juice MDA level than patients with chronic gastritis. As a whole, patients with gastric intestinal metaplasia and gastric cancer postsurgical resection also had significantly higher MDA levels in gastric juice as compared to patients with chronic gastritis (P < .01). However, the difference of gastric juice MDA levels between gastric intestinal metaplasia and gastric cancer postsurgical resection was not significant.

CONCLUSION

Malondialdehyde in gastric juice could be used as a potential diagnostic biomarker for H. pylori infection and associated gastric diseases. The gastric juice MDA levels increased proportionally with the severity of gastric diseases.

The Prolidase Activity, Oxidative Stress, and Nitric Oxide Levels of Bladder Tissues with or Without Tumor in Patients with Bladder Cancer

This study was designed to evaluate the malondialdehyde (MDA), glutathione (GSH) and nitric oxide (NO) levels, and also prolidase, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) enzyme activities in malignant and benign cancers of bladder tissue. A total of 59 patients admitted to our clinic due to microscopic or macroscopic haematuria, were prospectively included in the study. Because of some reasons (no request to participate in the study, the inability to reach, other malignancies, alcohol consumption, metabolic disease), eight patients were excluded from study. Of the 51 patients, 25 were bladder tumor patients, and 26 were patients without cancers. The bladder tissue samples were obtained from all patients under anesthesia (spinal, epidural or general) for the measurement of MDA, GSH and NO levels, and prolidase, GSH-Px and SOD enzyme activities. Among the patients with bladder cancers, 7 patients were females and 18 patients were males, with an average age of 68.4 ± 2.49. Among patients without tumors, 6 patients were females and 20 patients were males, with an average age of 58 ± 2.05. In patients with bladder tumors, the oxidants (MDA, NO, prolidase) were higher, and the antioxidants (SOD, GSH, GSH-Px) were lower than those in patients without tumors. It was concluded that the oxygen free radicals play a role in the etiology of bladder cancers similar to many other tumors and inflammatory conditions. Therefore, we assume that antioxidants may provide benefits in the prevention and treatment of bladder cancer.

Flavonoids from tartary buckwheat induce G2/M cell cycle arrest and apoptosis in human hepatoma HepG2 cells

The cytotoxicity and antioxidant activity on human hepatoma cell line HepG2 of three flavonoids homogenous compounds from tartary buckwheat seeds and bran, namely quercetin, isoquercetin, and rutin, were investigated. The total antioxidant competency detection results indicated that the antioxidant capacity of quercetin was the strongest in a biological response system. A [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay showed that quercetin exhibited the strongest cytotoxic effects against the HepG2 cell line. Flow cytometric analysis indicated that quercetin significantly increased the production of reactive oxygen species, and led to the G2/M phase arrest accompanied by an increase of apoptotic cell death after 48 h of incubation. Quercetin-induced cell apoptosis was shown to involve p53 and p21 up-regulation, Cyclin D1, Cdk2, and Cdk7 down-regulation. These results suggested that the induction of G2/M arrest, apoptosis, and cell death by quercetin may associate with increased expression of p53 and p21, decrease of Cyclin D1, Cdk2, and Cdk7 levels, and generation of reactive oxygen species in cells. This study will help to better understand and fully utilize medicinal resources of plant flavonoids.

Serum paraoxonase-1 enzyme activities and oxidative stress levels in patients with esophageal squamous cell carcinoma

OBJECTIVES

Oxidative stress is well recognized to play a role in the pathogenesis of many diseases, including cancers. Paraoxonase-1 (PON1) is implicated in the elimination of carcinogenic lipid-soluble radicals produced by lipid peroxidation. Reports on PON1 activities in patients with cancer are conflicting. The aim of this study was to investigate serum antioxidant enzyme activities and oxidative stress levels in patients with esophageal squamous cell carcinoma (ESCC).

PATIENTS AND METHODS

Thirty-two patients with ESCC and 33 healthy controls were enrolled. Serum malondialdehyde (MDA) levels and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GR), paraoxonase, and arylesterase activities were measured spectrophotometrically.

RESULTS

Serum paraoxonase, arylesterase, SOD, activities, GSH-Px, and GR activities were significantly lower in patients with ESCC than in controls (all, P < 0.05), whereas serum MDA levels were significantly higher (P < 0.05). Serum MDA levels were significantly correlated with paraoxonase (r = -0.572, P < 0.001) and arylesterase activities (r = -0.597, P < 0.001) in patients with ESCC.

CONCLUSIONS

This study indicated that ESCC is associated with increased oxidative stress and decreased antioxidant enzyme activities. Decreased serum PON1 enzyme activities may play a role in the progression and/or development of ESCC. Further studies are required to clarify these results.

Serum prolidase activity, oxidative stress, and antioxidant enzyme levels in patients with renal cell carcinoma

OBJECTIVES

Prolidase is a member of the matrix metalloproteinase family. It plays a vital role in collagen turnover, matrix remodeling, and cell growth. Reactive oxygen species (ROS) have been implicated in the pathogenesis of various diseases, including cancers. Oxidative stress can cause tumor angiogenesis and may be carcinogenic. However, the relationship between antioxidant capacity and various cancers has been researched in several clinical trials. In our study, we aimed to identify serum prolidase activity, oxidative stress, and antioxidant enzyme levels in patients with renal tumors and to evaluate their relationships with each other.

MATERIALS AND METHODS

A total of 37 male patients with renal cell cancer and with a mean age of 56.28 ± 3.1 were included in the study. The control group comprising 36 male patients (mean age 56.31 ± 2.9) was randomly selected among the volunteers. Serum samples for measurement of superoxide dismutase (SOD), glutathione peroxidase (GSHPx), glutathione-S-transferase (GST), malondialdehyde (MDA), glutathione (GSH), and prolidase levels were kept at -20°C until they were used.

RESULTS

Serum prolidase activity and MDA levels were significantly higher in renal cancer patients than in controls (all, p < 0.05), while SOD, GSHPx, and GST levels were significantly lower (p < 0.05).

CONCLUSION

Our results indicate that increased prolidase seems to be related to increased oxidative stress along with decreased antioxidant levels in renal cancer.

A non-surgical method for induction of lung cancer in Wistar rats using a combination of NNK and high dietary fats

Lung cancer is one of the most common malignant neoplasms all over the world. Smoking and a number of constituents of tobacco are responsible for development of lung tumours; however, the deleterious effects of tobacco-derived carcinogen, nitrosamine 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (nicotine-derived nitrosamine ketone (NNK)) remain unmatched. We report the development of a novel rodent model by administering multiple doses of NNK to male Wistar rats and feeding them with high-fat and low-protein diet. Tumour cells in lungs were observed in approximately 98 % rats after 8 months of NNK treatment, as evident by histopathological analysis. This rodent model showed slow progression of lung tumours which has helped us to assess early indicators of oxidative damage in lungs by studying the levels of lipid peroxidation and antioxidant parameters. LPO was elevated by 46.94 %, SOD, CAT, GSH and GR activity was decreased by 48.67 %, 22.04 %, 21.46 % and 20.85 %, respectively in serum of NNK treated rats when compared with control. These findings suggest that increased oxidative stress can represent a risk factor for the development of chronic disease in early future. This new animal model is an attempt to greatly facilitate studies of the pathophysiology, biochemistry and therapy of lung cancer.

Non-enzymatic post-translational protein modifications and proteostasis network deregulation in carcinogenesis

Organisms are constantly challenged by stressors and thus the maintenance of biomolecules functionality is essential for the assurance of cellular homeostasis. Proteins carry out the vast majority of cellular functions by mostly participating in multimeric protein assemblies that operate as protein machines. Cells have evolved a complex proteome quality control network for the rescue, when possible, or the degradation of damaged polypeptides. Nevertheless, despite these proteostasis ensuring mechanisms, new protein synthesis, and the replication-mediated dilution of proteome damage in mitotic cells, the gradual accumulation of stressors during aging (or due to lifestyle) results in increasingly damaged proteome. Non-enzymatic post-translational protein modifications mostly arise by unbalanced redox homeostasis and/or high glucose levels and may cause disruption of proteostasis as they can alter protein function. This outcome may then increase genomic instability due to reduced fidelity in processes like DNA replication or repair. Herein, we present a synopsis of the major non-enzymatic post-translation protein modifications and of the proteostasis network deregulation in carcinogenesis. We propose that activation of the proteostasis ensuring mechanisms in premalignant cells has tumor-preventive effects, whereas considering that over-activation of these mechanisms represents a hallmark of advanced tumors, their inhibition provides a strategy for the development of anti-tumor therapies. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.

Effects of 2-amino-1-methyl-6-phenylimidazo [4, 5-b] pyridine (PhIP) on histopathology, oxidative stress, and expression of c-fos, c-jun and p16 in rat stomachs

2-Amino-1-methyl-6-phenylimidazo [4, 5-b] pyridine (PhIP) is one of the most abundant heterocyclic amines (HCAs) generated from overcooking meat at high temperatures. To understand the possible mechanism of PhIP-associated stomach cancer, the effects of PhIP on morphology, oxidative stress, gene expression of c-fos, c-jun and p16 in rat stomachs were investigated. The results showed that (1) 15mg/kg body weight PhIP induced obvious histopathological changes in gastric mucosa; (2) PhIP (10 and/or 15mg/kg) significantly decreased superoxide dismutase (SOD) and glutathioneperoxidase (GPx) activities, while increased catalase (CAT) activity compared with the control. With the elevated doses of PhIP, malondialdehyde (MDA) contents, protein carbonyl (PCO) contents and DNA-protein crosslinks (DPC) coefficients were significantly raised in a dose-dependent manner; (3) PhIP at the doses of 10mg/kg and/or 15mg/kg significantly inhibited p16 mRNA and protein expression, whereas enhanced c-fos and c-jun expression relative to control. The data indicated that PhIP could cause stomach injury, oxidative stress in rat stomachs as well as the activation of c-fos and c-jun and inactivation of p16, which may play a role in the pathogenesis of PhIP-associated stomach cancer.

Serum prolidase activity, oxidative stress, and nitric oxide levels in patients with bladder cancer

Objectives

Prolidase is a member of the matrix metalloproteinase family. It plays a major role in collagen turnover, matrix remodeling and cell growth. Nitric oxide (NO) regulates many processes such as collagen synthesis and matrix remodeling. Thus, NO may augment angiogenesis, tumor invasion, and metastasis. The aim of this study was to investigate total antioxidant status (TAS), malondialdehyde (MDA) and NO levels in patients with bladder cancer and to determine their relationship with prolidase activity.

Design and methods

Thirty-five patients with bladder cancer and 32 controls were enrolled. Serum TAS, MDA, prolidase activity and NO levels were determined.

Results

Serum prolidase activity, NO levels and MDA levels were significantly higher in bladder cancer than controls (all, P < 0.05), while TAS levels were significantly lower (P < 0.05).

Conclusions

Our results show that increased prolidase seems to be associated with increased NO levels and oxidative stress along with decreased antioxidant levels in bladder cancer.

Oxidative Products of Proteins and Antioxidant Potential of Thiols in Gastric Carcinoma Patients

It has been suggested that oxidative stress defined as a shift in antioxidant/oxidant balance towards oxidants is associated with the pathogenesis of many diseases, including carcinogenesis. Reactive oxygen species can induce carcinogenesis via injury to macromolecules such as DNA, carbohydrates and proteins. Forty primary gastric carcinoma patients and 40 healthy controls were included in the study. Advanced oxidation protein products, total thiols, total protein, albumin in plasma, % hemolysis in RBC suspension and glutathione in both whole blood and plasma were estimated. Our studies demonstrated a significant increase in advanced oxidation protein products, % hemolysis (p=0.033), A:G ratio (p=0.003) and a highly significant decrease in blood glutathione (p=0.036), total thiols (p=0.001), plasma thiols other than glutathione and total antioxidant activity. The findings suggest that gastric carcinoma is associated with oxygen derived free radicals accumulation, and depletion of total antioxidant activity has lead to oxidative stress and advancement of oxidative-antioxidative disorders followed by progression of gastric cancer.

Chapter 9: Oxidative stress in malignant progression: The role of Clusterin, a sensitive cellular biosensor of free radicals

Clusterin/Apolipoprotein J (CLU) gene is expressed in most human tissues and encodes for two protein isoforms; a conventional heterodimeric secreted glycoprotein and a truncated nuclear form. CLU has been functionally implicated in several physiological processes as well as in many pathological conditions including ageing, diabetes, atherosclerosis, degenerative diseases, and tumorigenesis. A major link of all these, otherwise unrelated, diseases is that they are characterized by increased oxidative injury due to impaired balance between production and disposal of reactive oxygen or nitrogen species. Besides the aforementioned diseases, CLU gene is differentially regulated by a wide variety of stimuli which may also promote the production of reactive species including cytokines, interleukins, growth factors, heat shock, radiation, oxidants, and chemotherapeutic drugs. Although at low concentration reactive species may contribute to normal cell signaling and homeostasis, at increased amounts they promote genomic instability, chronic inflammation, lipid oxidation, and amorphous aggregation of target proteins predisposing thus cells for carcinogenesis or other age-related disorders. CLU seems to intervene to these processes due to its small heat-shock protein-like chaperone activity being demonstrated by its property to inhibit protein aggregation and precipitation, a main feature of oxidant injury. The combined presence of many potential regulatory elements in the CLU gene promoter, including a Heat-Shock Transcription Factor-1 and an Activator Protein-1 element, indicates that CLU gene is an extremely sensitive cellular biosensor of even minute alterations in the cellular oxidative load. This review focuses on CLU regulation by oxidative injury that is the common molecular link of most, if not all, pathological conditions where CLU has been functionally implicated.

Lipid peroxidation and antioxidant enzyme activities in cancerous bladder tissue and their relation with bacterial infection: a controlled clinical study

It is well known that antioxidants and reactive oxygen species play an important role in carcinogenesis. In this study, we attempted to evaluate antioxidant enzyme activities and lipid peroxidation levels in cancerous bladder tissue and to determine their relationship with bacterial infection. Bacterial culture was made from all urine samples using Blood and Eosin Methylene Blue agars for checking the presence of bacterial infections. We measured thiobarbituric acid reactive substances (TBARs) and activities of xanthine oxidase (XO), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and catalase (CAT) in cancerous tissues of 25 bladder cancer patients, in noncancerous adjacent bladder tissues of 13 out of these 25 patients, and in control bladder tissues of 15 patients with a non-neoplastic genitourinary disease. TBARs levels increased and XO, SOD, GSH-PX, and CAT activities decreased significantly in cancerous bladder tissues. TBARS, XO, and SOD levels were not significantly different between noncancerous adjacent tissue and control bladder tissue. Statistically significantly lower GSH-PX and higher CAT activities were observed in noncancerous adjacent bladder tissue compared with cancerous tissue. GSH-PX level of tumor tissue was correlated significantly with tumor grade (r=-0.425, P=0.034). Results suggested that pathway activity of free radicals were accelerated in the cancerous human bladder tissues via increased TBARs levels and decreased enzyme activities of XO, SOD, GSH-PX, and CAT, which implicated a severe exposure of cancerous tissues to oxidative stress.

Glutathione level and glutathione-dependent enzyme activities in blood serum of patients with gastrointestinal tract tumors

OBJECTIVES

Glutathione (GSH) and enzymes cooperating with it - glutathione peroxidase (GSHPx), glutathione S-transferase (GST) and glutathione reductase (GSHR) - play crucial role in cell defence against reactive oxygen species (ROS), which are implicated in tumor disease. The aim of this study was to determine if neoplastic diseases of gastrointestinal tract may influence blood GSH level and its dependent enzyme activity.

DESIGN AND METHODS

Blood serum was obtained before and after surgery from patients with gastric, liver and colorectal cancers, and colorectal cancer liver metastases. Lipid peroxidation and GSH levels, and GSH-dependent enzyme activities were determined by means of spectrophotometric methods.

RESULTS

Increased level of lipid peroxidation and significant differences in GSH level and GSHPx, GST and GSHR activities were observed in serum taken before and after surgery from patients with gastrointestinal tract tumors compared to those in control serum (from healthy blood donors).

CONCLUSIONS

Increase of lipid peroxidation and changes in GSH level and related enzyme activities, suggest oxidative stress in serum of patients with gastrointestinal tract tumor causes, which probably arise as a result of enormous production of ROS in the system. These alterations reflect the presence of functional defence mechanism against oxidative stress related firmly to the glutathione metabolism.